Astophotography Stretching

[extremenewby]

I am totally new to Affinity, prev used Photoshop, which since the Catalina upgrade no longer works, and was equally new to stretching astrophotos until recently, but in PS this entailed using the 3 tabs under the histogram to bring out the detail. In Affinity there seem to be only 2 equivalent adjustments (or so it seems to me), the black level and the white level. Therefore is it possible in Affinity to stretch the histogram? By stretching see the first part of this You Tube video if that is allowed here.

 

[James Ritson]

Hi @extremenewby, on Affinity Photo's Levels adjustment dialog you'll want to use the Gamma slider as an equivalent to Photoshop's mid-point slider.

If you have any other questions about editing astrophotography please ask, I've been working with various deep sky imagery lately and adapting various techniques to an equivalent approach in Affinity Photo. Hope that helps!

[extremenewby]

Thanks , I'll give it a go.

[Dmisisco]

I have an add-on question to this topic.  I too have been trying to adapt PS processes to Affinity.  In many PS tutorials that address stretching for astrophotography they do it in increments, a little at a time.  Does this concept work in Affinity as well?  I've seen some amazing images that have come out of PS that I just can't seem to recreate in Affinity.

[Planet30]

I had the same question. Coincidentally, I also want to stretch an image of the fascinating Veil nebula. Tricky to stretch and to adjust, due to its "high dynamic range"

For applying multiple times the "Curve Adjustment", do the following:

• Apply curve adjustment once => It will create the curve-adjustment layer.
• Then go to the Layers tab.
• Right-click on the curve adjustment you just applied.
• Click on "duplicate" in the context menu/list.
• A new curve adjustment has been added to the Layer.
• Double-click on this new curve adjustment layer to further stretch and alter the histogram 🙂

You can duplicate the curve adjustment layer as many times as you want to create multiple stretching iterations.

I hope this helps.

Edited July 12, 2021 by Planet30

[Planet30]

Actually, a more appropriate adjustment for histogram stretching is the "Levels Adjustment". You can also apply it multiple times consequetively, the same way as explained in the previous post by duplicating the Levels-Adjustment layer.